Re: SegmentedControl: Warning: Unable to show more than 4 allowed segments on the screen.

Ah, somehow I missed the fact that only 4 of my 5 segments were being displayed in the UI preview, that should have been a hint. So this is just a warning.

Something else that was throwing me off was that my UI wasn't displaying when I actually loaded it in the simulator, but I think that's because I needed to have a Page at the top-level of main.qml, not a bare Container.